Usiminas recently introduced the new core making simulation software MAGMA C+M as part of their strategy to establish robust designs and processes for their core production line. The first project the software was applied to was already in progress at that time. Therefore, the main goal was to optimize the process conditions for the existing tooling lay-out.
This core, called the thin waist core, represents some of the biggest challenges in Usiminas’ core production: its length (920 mm), substantial changes in the sand flow direction during blowing, the need to fill certain parts of the core through counter-flow and big variations in the cross section within the core.
First trials showed problems with the process, which led to a complete collapse of the lower part of the core. The core blowing and curing steps for the PU coldbox process were analyzed, making it possible to draw preliminary conclusions regarding the existing defects.
The lack of core strength was related to a poor curing process. The first simulation already showed that the problematic regions experienced only very low curing gas concentrations during gassing, which was the root cause for the failure.